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37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
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During the descent, an air carrier flight crew was asked if they were leveling at an altitude that was above what they believed they had been assigned to descend to, and had read back. During the time lapse between the controller's intervention and the flight crew's response, the aircraft descended 300 ft below the altitude that the controller now wanted them to maintain.
| Attributes | |
| ACN | 332660 |
| Time | |
| Date | 199604 |
| Day | Thu |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : bos |
| State Reference | MA |
| Altitude | msl bound lower : 16700 msl bound upper : 17000 |
| Environment | |
| Flight Conditions | Mixed |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : mmid |
| Operator | common carrier : air carrier |
| Make Model Name | Commercial Fixed Wing |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent other |
| Route In Use | enroute airway : zbw |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 155 flight time total : 11000 flight time type : 4000 |
| ASRS Report | 332660 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 35 flight time total : 5000 flight time type : 35 |
| ASRS Report | 332940 |
| Events | |
| Anomaly | aircraft equipment problem : less severe altitude deviation : overshoot other anomaly other |
| Independent Detector | other controllera |
| Resolutory Action | controller : issued new clearance flight crew : overcame equipment problem other |
| Consequence | Other |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | other |
Narrative:
During the arrival into the boston area we were given multiple stepdown altitudes of FL210, FL190, 17000 ft, and 14000 ft. It was during our passing 17000 ft that approach asked if we were leveling at 17000 ft. We were passing 16800 ft on our way down to 14000 ft (the altitude we were last cleared to, and read back to ATC). We were advised of traffic at 12 O'clock, 5 mi, at 16000 ft. We immediately climbed to 17000 ft. We bottomed out at 16700 ft. I can only assume that this was a last second altitude change due to traffic. Contributing to this is our arrival against the outbounds with multiple leveloffs in a short time span. Supplemental information from acn 332940: a possible communication error may have occurred. It is also important to note that we had multiple transponder or altimeter problems during our flight from mem to bos which may have contributed (at least 4 noted).
Original NASA ASRS Text
Title: DURING THE DSCNT, AN ACR FLC WAS ASKED IF THEY WERE LEVELING AT AN ALT THAT WAS ABOVE WHAT THEY BELIEVED THEY HAD BEEN ASSIGNED TO DSND TO, AND HAD READ BACK. DURING THE TIME LAPSE BTWN THE CTLR'S INTERVENTION AND THE FLC'S RESPONSE, THE ACFT DSNDED 300 FT BELOW THE ALT THAT THE CTLR NOW WANTED THEM TO MAINTAIN.
Narrative: DURING THE ARR INTO THE BOSTON AREA WE WERE GIVEN MULTIPLE STEPDOWN ALTS OF FL210, FL190, 17000 FT, AND 14000 FT. IT WAS DURING OUR PASSING 17000 FT THAT APCH ASKED IF WE WERE LEVELING AT 17000 FT. WE WERE PASSING 16800 FT ON OUR WAY DOWN TO 14000 FT (THE ALT WE WERE LAST CLRED TO, AND READ BACK TO ATC). WE WERE ADVISED OF TFC AT 12 O'CLOCK, 5 MI, AT 16000 FT. WE IMMEDIATELY CLBED TO 17000 FT. WE BOTTOMED OUT AT 16700 FT. I CAN ONLY ASSUME THAT THIS WAS A LAST SECOND ALT CHANGE DUE TO TFC. CONTRIBUTING TO THIS IS OUR ARR AGAINST THE OUTBOUNDS WITH MULTIPLE LEVELOFFS IN A SHORT TIME SPAN. SUPPLEMENTAL INFO FROM ACN 332940: A POSSIBLE COM ERROR MAY HAVE OCCURRED. IT IS ALSO IMPORTANT TO NOTE THAT WE HAD MULTIPLE XPONDER OR ALTIMETER PROBS DURING OUR FLT FROM MEM TO BOS WHICH MAY HAVE CONTRIBUTED (AT LEAST 4 NOTED).
Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.